A Primer on Lagerbier

July 1, 2012 By Keith Klemp

I am an unabashed lager lover. My first beer epiphany came from a glass of Hacker-Pschorr Dunkel in the mid-1970s. A few years later, homebrewing brought the giddy realization that I could brew my own. Much has changed on the homebrew front in the past 25 years, making the chasm between commercial and homebrewed lagers a matter of brewing skill. The equipment and know-how is the same, but the availability of top-notch ingredients has eliminated all compromise. We now have the option of making authentic, classic versions with ingredients from Germany, the Czech Republic, Belgium, the United States, Canada and England. The initial hardware investment, a refrigerator or freezer unit and temperature regulator, is modest and all that is needed beyond routine brewing equipment. A little patience and extra attention will also help.

The term lager is a misnomer of sorts. By default it has come to mean “bottom-fermented.” Lagern is German for storage and refers specifically to the post-fermentation cold-conditioning period. For the sake of familiarity and consistency, we’ll refer to traditional bottom-fermented, fully lagered beers as lager, lagerbier or bottom-fermented, all of which have become interchangeable.

Hardware

The main considerations for brewing lagers are fermentation/temperature, yeast choice/handling, and timing. In summary, they are fermented between 46 and 58 degrees, warmed briefly to reduce diacetyl and then lagered at 32 to 40 degrees. Temperature control is critical, and the best way to achieve this is with a plain refrigerator or freezer and a temperature controller/regulator. The latter can be purchased for $50 to $100 at any homebrew shop. Regulators vary in capability, but not in effectiveness. They operate by bypassing the internal thermostat of the refrigerator with a remote probe. Single-degree adjustments are possible.

Any functioning refrigerator or freezer will work fine if you have a reliable regulator. A tight door seal and working compressor are the only requirements. If you don’t care about cosmetics and are resourceful, fridges and old freezers can be found cheap or even free. When they wear out, donate them to the local appliance restorer for parts. This repurposing keeps them out of the landfill for as long as possible. With all of the internal shelves and baskets removed, they are surprisingly spacious and can be used for hop or beer storage or double as a kegerator.

Software

I am a firm believer in simplicity and subscribe to the notion that nuance and exceptional complexity are possible with thoughtful technique and deft use of few ingredients. There are many base and specialty malts made specifically for brewing lagerbiers. German and Bohemian base malts are the most authentic, but Belgian, American, Canadian and even British malts are excellent. Lagers are perfect candidates for single-malt brews and, coupled with a simple schedule of hops and a well-chosen yeast, demonstrate brewing art at its most spartan. Pilsner, Vienna and Munich malts, all of which are quite different from one another, can be used for the single-malt lagers as they were intended. Blends of those three alone can be used to craft base-malt beers. Rauchmalz (smoked malt) is also a base malt and can be used on its own, but is even better when combined with Munich or Vienna malts. Specialty malts, especially those from Germany, are perfect for additional character. De-bittered roasted malts and grains add color without harshness to dunkels or bocks, or a firm dose of peaty roast to schwarzbier or Baltic porters. For extract brewing, light malt extracts made from pilsner malt or amber malt extract made with chewy, toasty Munich malt can be used on their own or blended in any ratio. Combining these with the previously mentioned lager-purposed specialty malts will bring any bottom-fermented style within easy reach. Partial-mashers can easily combine the two strategies. Thanks to a general interest in home and microbrewing, the range of grain and malt ingredients tailored to lager brewing is growing, especially in North America.

As for hops, three of the noble four, Saaz, Hallertauer Mittelfrueh and Tettnang are traditional lager hops, as is Hersbrucker, and are famous for their soft herbal and floral aromatics. There are also some new types being cultivated in Germany that are worth investigating. Other than pilsner, there is no lager style that showcases hops, but that is not to say they aren’t important, as noble hops give authentic roundness, even in low doses, that define the classics. If you are looking for something to accent a North American lager, turn to one of the Pacific Northwest cultivars with noble pedigree, such as Citra, Crystal, Mount Hood, Liberty, Santiam, Vanguard or U.S.- grown Hallertauer, Tettnanger or Saaz.

Choice of yeast can be quite important, especially if you are seeking a specific character or trait. All bottom fermenters (Saccharomyces pastorianus) work in roughly the same temperature range and have subtle differences among them, but are far less diverse than top fermenters (Saccharomyces cerevisiae), and produce none of the dozens of estery and spicy byproducts associated with the latter. Liquid yeast suppliers list about two options, with complete performance and sensory specs. There are also dried bottom-fermenting yeasts for those who are more comfortable with that platform.

Some extra attention is needed to optimize yeast activity. Bottom fermentation is colder and significantly slower than top, so a vigorous start is imperative. Double the usual volume of starter, 2 liters for 5 gallons of beer, to increase the cell count. Ferment your starter at or slightly above the planned fermentation temperature. You can pitch when the batch wort is slightly above fermentation temperature (60 to 65 degrees) and then reduce temperature immediately to fermentation conditions. Or pitch at the target fermentation temp. The trade-off is quicker liftoff and more diacetyl production (warm method) versus slower liftoff and less diacetyl production (cool method). If your starter is properly prepared and the wort has been vigorously aerated, the cool method should work fine. If using dried yeast, use two rehydrated packages per 5 gallons of beer.

The Operating System

Fermentation and lagering are a simple matter of regulation and monitoring. Set your regulator to 50-52 degrees for primary fermentation. Lager yeasts produce sulfur compounds during fermentation, but they will dissipate with proper lagering. Primary should last about seven to 10 days for lower-gravity wort to as long as three or four weeks for higher-gravity ones. The end point of primary signals the time to begin the diacetyl rest, so steal a sample to taste and take a gravity reading to ensure completion. If it is lagging, you can let it sit for a few more days, which won’t have any adverse effects, or raise the temperature a couple of degrees.

Once primary fermentation has finished, perform a diacetyl rest by raising the temperature to 57-60 degrees for one to two days. There may be some outgassing or minor fermentation, but it is important to proceed to cooling after no more than two days. Prepare the wort for lagering by dropping the temp to 40 degrees gradually over a few days to drop the yeast. When the wort is fairly clear, rack to your lagering vessel, carboy or corny keg, and take the temperature to 32-35 degrees over a few days. Leave as little air space as possible in the lagering container. This is where the magic of lagering takes place, slowly metabolizing spent yeast remnants and consuming nasty metabolites, scrubbing the wort clean. Lagering also precipitates soluble proteins, effectively clarifying the beer. Lagering times will vary from three weeks for lower-gravity brews to eight weeks or more for strong ones. Once finished, the beer can be kegged, carbonated and consumed as usual. If you bottle, dose the beer with some fresh lager yeast (one propagator smack pack, part of a pitchable tube or half a pack of dried lager yeast) and your priming solution and bottle-condition for a few weeks at 45 to 55 degrees.